The present invention generally relates to circuits for simultaneously obtaining in parallel signals constituting a time division multiplexed signal, and more particularly relates a circuit for simultaneously obtaining in parallel signals constituting a time division multiplexed signal such as color difference signals constituting a line-sequential color difference signal in a color image pickup device.
Color television cameras using interline transfer charge coupled devices (CCDs) may be divided into two kinds depending on the mode with which the signal charge is stored, that is, a frame integrated mode in which the signal charge is stored for a time period of one frame (1/30 second) by one photodiode and a field integrated mode in which the signal charge is stored for a time period of one field (1/60 second). Compared to the field integrated mode, the frame integrated mode is advantageous in that it is possible to obtain a high vertical resolution. On the other hand, the field integrated mode is advantageous in that it is possible to eliminate the equivalent after image caused by the interlace, that is, a disadvantage of the frame integrated mode, and it is also possible to reduce the flicker in the vicinity of the vertical resolution limit. However, as will be described later on in the present specification in conjunction with the drawings, the light utilization efficiency and the luminance signal characteristic are improved according to the field integrated mode employing a complementary color filter when compared to the frame integrated mode employing a primary color filter, but there is a disadvantage in that the signal-to-noise (S/N) ratio of the color signal is poor because the modulation degree of the color signal decreases. Accordingly, it is desirable to improve the S/N ratio of the color signal.